Testing Informant Discrepancies as Predictors of Early Adolescent Psychopathology: Why Difference Scores Cannot Tell You What You Want to Know and How Polynomial Regression May

Multiple informants commonly disagree when reporting child and family behavior. In many studies of informant discrepancies,
researchers take the difference between two informants’ reports and seek to examine the link between this difference score
and external constructs (e.g., child maladjustment). In this paper, we review two reasons why difference scores cannot serve
as unambiguous predictors of outcomes. Further, we use polynomial regression analyses to both test the validity of difference
scores and provide a more direct test of the hypothesis that discrepancies in parent and child reports predict child psychopathology.
Data from 218 parent-adolescent dyads (M adolescent age = 11.5 years, 51 % female; 49 % European American, 47 % African American) were used to predict adolescent-reported
antisocial behavior and depression from parent and adolescent reports of parent-adolescent conflict, parental knowledge, parental
acceptance, adolescent rule-breaking behavior, and adolescent pubertal development. Results demonstrate that analyses using
difference scores do not provide valid tests of the utility of informant discrepancies in predicting adolescent psychosocial
maladjustment. However, interaction terms in polynomial regression analyses provide evidence that informant discrepancies
predict child psychopathology. Parent-adolescent informant discrepancies predict adolescent psychopathology but researchers
should avoid using difference scores to measure informant discrepancies. Polynomial regression analyses provide more comprehensive
and accurate tests of whether informant discrepancies predict child and adolescent psychopathology.